you are going about it wrong....instead of only changing your reps around,you need to focus on tri's,lats,upper back..these arethe muscles that will bring your bench up...i guarantee it.break the bench dowyour lats wil kick in at the bottom and get the bar moving,your shoulders will start to take over more in the mid part then your tri's will come in and lock the weight out...
try bringing the bar a little lower on your chest,tuck your elbows towards your sides a bit,stay tight with your lats while you lower the bar,come off your chest fast nad straight to the top.......also bring this to the powerlifting board,alot of my buddies post there and can also help you with this..............